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The role of the pyridoxine (vitamin B6) biosynthesis enzyme PDX1 in ultraviolet-B radiation responses in plants
Örebro University, Department of Natural Sciences. (Biokemigruppen)
Örebro University, School of Health and Medical Sciences.
National University of Ireland - Galway.
Örebro University, Department of Natural Sciences. (Biokemigruppen)ORCID iD: 0000-0003-3315-8835
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2011 (English)In: Plant physiology and biochemistry (Paris), ISSN 0981-9428, Vol. 49, no 3, 284-292 p.Article in journal (Refereed) Published
Abstract [en]

Ultraviolet-B radiation regulates plant growth and morphology at low and ambient fluence rates but can severely impact on plants at higher doses. Some plant UV-B responses are related to the formation of reactive oxygen species (ROS) and pyridoxine (vitamin B6) has been reported to be a quencher of ROS. UV-B irradiation of Arabidopsis Col-0 plants resulted in increased levels of PDX1 protein, compared with UV-A-exposed plants. This was shown by immunoblot analysis using specific polyclonal antibodies raised against the recombinant PDX1.3 protein and confirmed by mass spectrometry analysis of immunoprecipitated PDX1. The protein was located mainly in the cytosol but also to a small extent in the membrane fraction of plant leaves. Immunohistochemical analysis performed in pea revealed that PDX1 is present in UV-B-exposed leaf mesophyll and palisade parenchyma but not in epidermal cells. Pyridoxine production increased in Col-0 plants exposed to 3 days of UV-B, whereas in an Arabidopsis pdx1.3 mutant UV-B did not induce pyridoxine biosynthesis. In gene expression studies performed after UV-B exposure, the pdx1.3 mutant showed elevated transcript levels for the LHCB1*3 gene (encoding a chlorophyll a/b-binding protein of the photosystem II light-harvesting antenna complex) and the pathogenesis-related protein 5 (PR-5) gene, compared with wild type.

Place, publisher, year, edition, pages
Amsterdam: Elsevier , 2011. Vol. 49, no 3, 284-292 p.
National Category
Biochemistry and Molecular Biology
Research subject
URN: urn:nbn:se:oru:diva-3111DOI: 10.1016/j.plaphy.2011.01.003PubMedID: 21288732OAI: diva2:137027
This is a pre-print articleAvailable from: 2012-08-07 Created: 2006-09-21 Last updated: 2016-08-10Bibliographically approved
In thesis
1. Vitamin B6 as a potential antioxidant: a study emanating from UV-B-stressed plants
Open this publication in new window or tab >>Vitamin B6 as a potential antioxidant: a study emanating from UV-B-stressed plants
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Increased influx of solar UV-B radiation (280-320 nm), due to a decreasing stratospheric ozone layer, impacts severely on plants. Some of the UV-B effects on plants are related to stress induced by produced reactive oxygen species (ROS). Pyridoxine (vitamin B6) has been reported to be a potential quencher of ROS.

Previous studies have shown that the PDX1.3 gene (encoding a key enzyme in vitamin B6 biosynthesis) is up-regulated by UV-B. We showed that this up-regulation also occurs at the protein level in UV-B exposed Col-0 wild-type plants. Studies performed using pdx1 knock-out mutants of Arabidopsis thaliana showed elevated transcripts levels for LHCB1*3 and PR-5 compared with the Col-0 wild-type. The pdx1 knock-out mutants showed an increased sensitivity towards H2O2-stress, but no increased sensitivity towards low dose UV-B-stress.

To study the postulated role of pyridoxine as quencher of ROS in more detail, both theoretical and experimental studies were performed. Theoretical and experimental UV absorption spectra obtained at different protonation/deprotonation states of pyridoxine showed a very close resemblance at low and high pH. However, for the computational studies at physiological pH addition of counterions were required to accurately describe the experimental spectra.

When theoretically studying the reactivity of pyridoxine towards three different ROS, .OH, .OOH and .O2-, the hydroxyl radical (.OH) was shown to be the most reactive species, while the superoxide radical (.O2-) showed no reactivity towards pyridoxine.

In order to study the role of G-proteins in UV-B signal transduction pathways, UV-B irradiated G-protein mutants of Arabidopsis thaliana were studied. The regulation of the PDX1.3 gene was not affected in the G-protein mutants, regardless of the developmental stage of the plant. However, the expression of CHS was affected in the Ga subunit mutants.

Place, publisher, year, edition, pages
Örebro: Örebro universitetsbibliotek, 2006. 73 p.
Örebro Studies in Life Science, 3
Arabidopsis, UV-B irradiation, pyridoxine, vitamin B6, ROS
National Category
Chemical Sciences
Research subject
urn:nbn:se:oru:diva-625 (URN)91-7668-497-0 (ISBN)
Public defence
2006-10-12, HSL3, Örebro universitet, Örebro, 10:00 (English)
Available from: 2006-09-21 Created: 2006-09-18 Last updated: 2011-05-26Bibliographically approved

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